Check my design?

[Nishinga]

My design is inspired by noobtastic14's old build on the members builds page.

Below is a picture from his thread, and pretty much what im going for

Now here is a hand drawn picture of my design that will fit in my car attempting to fit like his

Dont laugh at my shitty picture

You get the idea of what im going for

It should be 7.5 ft3 internal before any displacement

2 4 inch aero ports tuned to 33hz

Planning on running a Fi SP4 18 in there.

What do you guys think, I probably need some serious help dont I...

[Cox]

if its 7.5 ft3, your gonna need a lot more then 2 4in aeros.

[CleanSierra]

if its 7.5 ft3, your gonna need a lot more then 2 4in aeros.

Not true. You port to the sub, not the airspace.

[Cox]

if its 7.5 ft3, your gonna need a lot more then 2 4in aeros.

Not true. You port to the sub, not the airspace.

What parameter do you go off of to find out how much port you need ( if that makes sense how I said it)

[CleanSierra]

Xmax, cone area, and desired tuning frequency. I'm not saying that you are wrong in your thinking, but the "x amount of port per square foot" isn't the best rule of thumb. Two different subs, with far different specs, could sound COMPLETELY different in the same enclosure using this "port per square foot" logic. A sub with 33MM of Xmax would sound completely different than a same sized sub that only had 16MM Xmax in the same enclosure, using the same principles.

Because the OP is using a sub with plenty of Xmax, plus it's an 18 with a fairly low(average by the forum's standards) tune I'd agree that a little more port might be a good idea.

[Cox]

Xmax, cone area, and desired tuning frequency. I'm not saying that you are wrong in your thinking, but the "x amount of port per square foot" isn't the best rule of thumb. Two different subs, with far different specs, could sound COMPLETELY different in the same enclosure using this "port per square foot" logic. A sub with 33MM of Xmax would sound completely different than a same sized sub that only had 16MM Xmax in the same enclosure, using the same principles.

Because the OP is using a sub with plenty of Xmax, plus it's an 18 with a fairly low(average by the forum's standards) tune I'd agree that a little more port might be a good idea.

sorry for thread jack here, but which would require more port, more or less xmax and cone area?

[Nishinga]

according to the precision sound aero port calculator tuning 7.5ft3 to 33hz could be done with 2 4inch diameter flared ports 6.3 inches long.

Correct me if im wrong?

But as far as the design of the box goes dimensions and everything looks ok??

[Cox]

I wasn't saying you couldn't get the tuning with those, I meant there wouldn't be enough port area.

[ChevyBoy95]

2 6in ports IMO.

[CleanSierra]

2 6in ports IMO.

This

They might be long to get that tuning though